Method and device for controlled air injection into a vinification tank

ABSTRACT

A method and a device for air injection into a vinification tank (1) use air injection nozzles (2) installed therein. A rule is applied for automatic variation of injections with time, by a coordinated and combined action of the nozzles, so that for each of the installed nozzles the delivered air jets may be modulated in duration and frequency and combined with the jets delivered by the other nozzles according to a programmable sequence.

CROSS-REFERENCE TO RELATED APPLICATIONS

Continuation of U.S. patent application Ser. No. 15/521,487, anational-stage application of PCT/IB2015/058,506, filed 3 Nov. 2015,which claims benefit of Serial No. PO2014A000010, filed 2 Dec. 2014 inItaly and which applications are incorporated herein by reference. Tothe extent appropriate, a claim of priority is made to each of the abovedisclosed applications.

TECHNICAL FIELD

The present invention generally addresses the field of plants andequipment for the wine industry and particularly relates to a method ofcontrolled air injection into a vinification tank. The invention alsorelates to a device for implementing said method.

PRIOR ART

As is known, in the process of fermentation on skins, once the tank hasbeen filled with crushed red grapes, and as soon as fermentation starts,the skins separate from the liquid. The skins are pushed up by thecarbon dioxide released upon conversion of sugar into alcohol and form avery compact layer above the liquid, which is known as “cap”. Therefore,a few hours after the start of fermentation, the vinification tank willcontain an underlying liquid and a compact semi-solid over the liquid.

The cap must be frequently disaggregated for extraction of valuablecomponents (polyphenols and aromatic compounds), by leaching the skinswith the liquid as non-aggressively as possible to avoid skintrituration.

Arrangements have been long known and implemented in various technicalfields (waste treatment, wastewater treatment, beverage and fruit juicestorage, oil storage, etc.), for mixing the contents of large- andmedium-size tanks by injecting air therein from below. Nevertheless,such technique has been rarely used in the wine industry for breakingand hence wetting the cap formed above the liquid during fermentation ofred must.

Different techniques have been preferred heretofore, such as sprayingthe cap using a pump and a sprinkler, mechanical punch down, whichconsists in pushing the skins into the liquid using a plate, delestage,which consists in extracting part of the liquid by pumping it into atemporary tank, and pouring it back into the vinification tank using adisperser.

Air injection is rarely used for mixing in the process of fermentationon skins, because a tank containing must for fermentation on skins hasproblems completely differing from those of any other tank containingliquid to be mixed, and such technique cannot ensure quick, effectiveand extensive disgregration of the cap and wetting of skins, withoutcausing undesired side effects such as the formation of dregs.

Prior art air injection devices for use in the wine industry arebasically composed of a compressed air and/or inert gas generationand/or storage system, an air distribution system composed of pipes,fittings, filters and valves, the latter being controlled manually orthrough a programmable-logic control (PLC) system, and an air injectionsystem using nozzles that are designed to be located in the vinificationtank.

Traditionally, the oldest technical arrangement consists of a tubularrod having a manual cock and connected to the compressed air generationsystem. The rod is introduced into the tank from the top, through thecap, or from the bottom through a valve, whereupon the cock is manuallyopened and closed after a few seconds. The pressurized air flowintroduced into the liquid creates a strong local turbulence which risesto the surface and partially breaks the cap.

This arrangement is problematic in that a manual (or eventimer-operated) generation of a continuous air jet may provide a ratherviolent jet and yet cannot break the entire cap unless this operation isrepeated many times with the rod in various positions (which is onlypossible, moreover, if the rod is introduced from the top).

The effectiveness of this arrangement has been improved byvariable-frequency pulsed air injection. In other words, the frequencyof jets may be adjusted according to the desired effect, i.e. 10 jetsper minute, 20 jets per minute and the like. The frequency may bemanually adjusted by the user according to the effect that the user isobserving and to the change he/she makes to obtain something differentat the time of operation. This improves effectiveness while limiting airconsumption.

Nevertheless, the problem of these solutions is that they are notsusceptible to automation, but always require a manual action by anoperator to introduce the tubular rod into the tank, to observe theresult of air injection and to manually change the position of the rodand the frequency of air pulses for entirely wetting the cap. Thisresults in long application times and requires the use of skilledpersonnel to repeat the operation 4-8 times a day for each tank.

For automated air injection, liquid stirring techniques have been usedfor the must. In these techniques, nozzles are positioned on the bottomof the tank, and their number is proportional to the size of the tank.These nozzles have such construction that, under pulsed air control,they create bubbles that rise to the surface, mix the liquid content andpartially wet the cap.

When the number of nozzles is small, all the nozzles are actuated at thesame time. In large tanks, the nozzles are arranged in concentriccircles and are actuated by alternating the center and the odd circleswith the pair circles.

Nevertheless, this is not an optimal arrangement, because if the nozzlesare located proximate to the bottom of the tank, then the tank emptyingoperation at the end of fermentation for marc extraction becomes verycomplicated.

This “racking” operation at the end of fermentation consists in emptyingfirst the liquid and then the solid from the tank. Once the liquid hasbeen emptied, the cap deposits on the bottom and easy removal thereofrequires the bottom to be free of obstacles.

In view of facilitating this operation, most of the tanks used forfermentation on skins are equipped with a rotating extraction blade onthe bottom of the tank which pushes the solid toward an emptying door,once the liquid has been emptied, thereby avoiding the need foroperators to enter the tank and manually push the marc toward the doorusing blades or other tools.

In lieu of the extraction blade, a tank with a centered or off-centerconical bottom (a slant-bottom tank) is sometimes used for the marc tobe removed by gravity (self-emptying tanks). Only in this case, theprovision of nozzles on the bottom of the tank is not problematic.

Nevertheless, the effect of bubbles rising to the surface, as describedabove, is not adequate for breaking and wetting the cap, especially intall and narrow large-capacity tanks, having a cap as high as 2-3 m. Inthis case, bubbles are not able to disgregate and wet the entire cap.

A satisfactory cap wetting result can be only obtained with longtreatment times and a huge air flow. For this reason, all the abovemethods involve the problem of stripping of flavors and alcohol, as theyare partially carried away by the air flow. Thus, this arrangementeventually results in a negative effect, as it involves a flavor andalcohol loss.

AU2004101059 discloses an apparatus for injecting air into avinification tank, comprising an injector for injecting air into thetank, associated with a central controller. The tank may containmultiple nozzles, equipped with check valves, which are part and are fedby the same injector. An array of vinification tanks may be alsoprovided, each tank being equipped with its own air injector, which maybe independently controlled by the injector of another tank, through thecentral controller. As a result, each tank may undergo a different airinjection cycle, with an injection duration and an injection frequencyother than those of another tank. Nevertheless, the nozzles of each tankoperate according to the same air injection cycle, which may havevariable injection durations and frequencies, provided that thisvariability applies to all the nozzles in the tank at the same time.

FR2797271 discloses an apparatus for thermovinification (at 50-80° C.),in which maceration lasts from 30 to 60 minutes, and a conical-bottomtank is provided, with a cylindrical compressed-air distributorthereunder, having compressed-air nozzles on its side wall. Theinjection of compressed air through the distributor, which is controlledby a solenoid valve operated by a regulator device, has the purpose ofcreating a convection stream for homogenizing the mixture and enhancingthe diffusion of flavors, colors and useful substances (tannins,anthocyans) of the solid elements into the must.

U.S. Pat. No. 4,593,611 discloses a device for controlling vinificationtemperature, comprising heating means and cooling means external to thevinification tank, for circulation of the must therein according to agiven sequence. The thermally-treated must is reintroduced into the tankthrough distribution nozzles. The circulating must is aerated byinjection of compressed air into the circulation conduit, under thecontrol of an on-off valve.

DISCLOSURE OF THE INVENTION

The general object of the present invention is to provide a method ofcontrolled air injection into a vinification tank that can obviate thedrawbacks as noted above in prior art air injection methods.

A particular object of the present invention is to provide a method ofthe above mentioned type, affording air injection intensity control toadapt the effect on the cap to the type of grapes and to thefermentation stage, for more or less delicate disgregration of the cap.

Another object of the present invention is to provide a method of theabove mentioned type which uses a relatively small amount of air togenerate shock waves that can disgregrate the cap and then cause it tobe entirely flooded after a few seconds with no violent action thatmight have a skin-triturating effect.

A further object of the present invention is to provide a method of theabove mentioned type in which the flavor and alcohol stripping problemsof prior art methods are considerably reduced.

Yet another object of the present invention is to provide a device forimplementing the method of the invention.

According to an important feature, the invention provides a new way ofinjecting air into a vinification tank, with the application of a rulefor automatic variation of injections with time, by a coordinated andcombined action of the nozzles, which means that the delivered air jetsor pulses may be modulated in duration and frequency and combined,according to a programmable sequence, with the jets delivered by theother nozzles.

In other words, each nozzle in the tank is fed and actuatedindependently of the other nozzles in the same tank, but all nozzles arecoordinated by a program that controls both air delivery from eachnozzle to change the duration and frequency of the air jet with timeaccording to a specific predetermined modulation, and the deliverysequence of all the nozzles, which may be actuated one after another orin a partially overlapping manner, and even at the same time, with equalor different jet durations and frequencies.

According to particular embodiments of the invention, the nozzlesoperate in turn, one after the other, in alternating or partiallyoverlapping fashion, and each nozzle may be controlled to delivermodulated, intermittent air jets, particularly having a constant,increasing or decreasing duration, and either a constant frequency or afrequency that can be varied in predetermined or programmable ways.

According to another important characteristic, the invention provides adevice for air injection into a vinification tank, comprising at leastthree nozzles for injecting compressed air delivered through an airdistribution circuit having valves thereon for controlling the air flowdirected to each nozzle and microprocessor means acting upon saidcontrol valves. The air injection nozzles are installed in the tank at alevel not higher than one third of the total height of the tank, and themicroprocessor means are programmable to actuate the control valvesindependently of one another to vary, according to a predeterminedmodulation rule, the frequency and duration of the air jets delivered byeach nozzle and the delay time of each nozzle relative to the next onein the nozzle actuation sequence.

These and other features and the advantages of the method of controlledair injection into a vinification tank and the apparatus forimplementing said method according to the invention will be apparentfrom the following description of certain embodiments thereof, which isgiven by way of example and without limitation with reference to theannexed drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIGS. 1a and 1b are schematic sectional and side elevation views of avinification tank equipped with an air injection device according to afirst variant embodiment;

FIGS. 2a and 2b are schematic sectional and side elevation views of avinification tank equipped with an air injection device according to asecond variant embodiment;

FIG. 3 shows a detailed lateral sectional view of a side wall of aconcrete vinification tank with a nozzle of the air injection device ofthe invention mounted thereon;

FIG. 4 shows a side view of a nozzle installed on the outer side of thesidewall of a steel vinification tank;

FIG. 5 shows a side view of a nozzle installed on the outer side of thesidewall of a steel vinification tank;

FIGS. 6 and 7 show construction details of a nozzle that can be removedfrom the outside;

FIGS. 8 to 13 show graphic examples of time modulation of air injectionfrom the nozzles according to a controlled air injection method of thepresent invention.

EMBODIMENTS OF THE INVENTION

Referring now to FIGS. 1a, 1b and 2a, 2b , numeral 1 generallydesignates a vinification tank having at least three nozzles 2 on itsside wall, for injecting air into the liquid mass (must) contained inthe tank 1, as will be better explained hereinbelow.

FIGS. 1a and 1b show a vinification tank 1 equipped with threeair-injection nozzles 2, whereas FIGS. 2a and 2b show a vinificationtank 1 equipped with four air-injection nozzles 2.

The nozzles 2 are equally spaced and placed at a height h from thebottom of the tank 1, which does not exceed one third of the totalheight of the tank. The nozzles 2 are also connected to a compressed-airgenerating system 10 of conventional type, only schematically shown,through a compressed-air distribution circuit, generally referenced 3,comprising distinct supply lines for each nozzle, with valves 4installed thereon for control and regulation of the air flow supplied toeach of the nozzles 2. Microprocessor means 11 are further provided,which can be programmed to control and regulate, through the valves 4,the air flow injected into the tank 1 through each of the nozzles 2according to a predetermined program for controlling the modulation ofthe air jet durations and frequencies and the nozzle operation sequence,as described below.

As further shown in greater detail in FIG. 6, in the preferredembodiment of the invention, the nozzles are substantially shaped like awide L and particularly their outlet forms an angle of 110° to 180° withthe perpendicular to the side wall of the tank from which the nozzleinwardly projects.

The optimal angle of the nozzle is selected according to the selectedpositioning height of the nozzles and their distance from the cap. Forexample, if the nozzles 2 are installed on the side wall of the tank 1an angle of divergence ranging from 115° to 170° shall be deemedadequate and an angle ranging from 115° to 150° is preferred. FIG. 3shows an air injection nozzle 2 mounted to the side wall of a concretetank. Here, the nozzle 2 is mounted from the inside of the tank by ascrew or a snap-fit connection, or another suitable system, at the endof a sleeve 5 embedded in the tank wall and connected in turn, by itsouter end, to the air distribution circuit.

FIG. 4 shows a first way of mounting an air injection nozzle 2 to theside wall of a steel tank. Here, the nozzle is mounted from the outsideby fitting it through a sleeve 6 welded within a corresponding hole 7formed in the wall of the tank 1 and by fixing it to the sleeve 6 bymeans of an outer connecting ring nut 8.

FIG. 5 shows a second way of mounting an air injection nozzle 2 to theside wall of a steel tank. Here, the nozzle is mounted from the insideby inserting it into a sleeve 6 welded within a corresponding hole 7formed in the wall of the tank 1 and by fixing it to the sleeve 6 bymeans of an inner connecting ring nut 9.

FIGS. 6 and 7 show the detailed construction of a nozzle 2 with all theparts required for mounting it to a vinification tank 1 from theoutside, and particularly the sleeve 6 to be welded into the hole 7 ofthe tank 1 and the connecting ring nut 8 designed for cooperation with aring 12 which is rigidly joined to the shaft 2 a of the nozzle forfixing the nozzle to the tank wall. Advantageously a cylindrical block,e.g. made of Teflon, may be also provided with an antifouling purposebetween the shaft of the nozzle 2 and the sleeve 6, as shown in FIG. 6and referenced 13.

According to an important aspect, the present invention provides anoriginal method of injecting air through the above described nozzles 2,which affords optimized disgregration and thorough wetting of the cap.

The nozzle are sequentially actuated with a modulated delay time betweenone nozzle and the next. Furthermore, the duration and frequency of theair jets or pulses of each nozzle may be modulated independently of theother nozzles in the tank. Due to the particular combination of the twomodulations (duration and frequency on the one side and sequence on theother) a relatively small amount of air can generate shock waves thatdisgregrate the cap and later cause it to be entirely flooded.

The sequence modulation and the jet duration and frequency modulation,as well as their combination, may be programmed and modified to obtainedvarious action intensities, such that their effect on the cap may beadapted to the type of grapes and the fermentation stage(pre-fermentation, start, tumultuous, end, etc.).

Air is injected periodically multiple times a day, with timings selectedby the operator as needed and based on his/her experience and for eachnozzle, according to the present invention, in cyclic mode, i.e. thenozzles undergo one or more cycles of intermittent jets of programmedduration and frequency and are operated according to a sequence, alsoprogrammed, which may involve total alternation of the cycle of onenozzle to that of the previous one, or partial overlapping of the cyclesof the two successively operated nozzles.

The operating pressure of compressed air generally ranges from 2 to 7bar. The minimum duration of each air jet is 100 ms and its maximumduration is 15 seconds. The following examples, which are given withreference to FIGS. 8 to 13 show a few possible nozzle control modes,although it shall be intended that a number of additional modes may beselected by the skilled person as needed.

Example 1 Medium Action

A medium-intensity air injection action of the nozzles is desired.Referring to FIG. 8, the nozzles are operated to obtain an increasingmodulation, i.e. with intermittent jets of increasing duration. Namely,the nozzles are actuated in turn, one after the other. The second nozzlestarts a time [RU1-2] after the start of the first nozzle. The thirdnozzle starts a time [RU2-3] after the start of the second nozzle. Sincethe second nozzle starts when the first nozzle is still operating, acrossed combination is obtained. Each nozzle is associated with a presetautomatic frequency variation (modulation).

Here, there is an increasing modulation as both pause times andactuation times increase. In a variant embodiment, only the pause timeor the actuation time may be increased. This nozzle control modegenerates a rotation moment in the fluid, which amplifies the crumblingeffect to the entire cap.

Example 2 Mild Action

A milder-intensity air injection action from nozzles is desired, ascompared with the mode as described under Example 1. Referring to FIG.9, this modulation is identical to the previous one concerning theindividual nozzles, but nozzle actuations do not overlap, which meansthat the next nozzle starts once the previous one has stopped (alternatecombination). The effect of this operating mode is, as mentioned above,much milder than that obtained with the operating mode as describedunder Example 1, but is adequate in certain cases.

Example 3 Holding Action

This nozzle control mode, as shown in FIG. 10 provides constantmodulation with constant actuation times and constant pause times foreach jet of each nozzle, as well as alternate combinations, with thenozzles never starting together but successively, one after the other.The effect of this operating mode is even milder than that of Example 2,and does not break the cap unless it has already broken by previousactions. It shall be noted that this operating mode is similar to whatcan be implemented using a prior art device, with the significant,important difference that, in this example, multiple nozzles areactuated in turn, successively one after the other.

Example 4 Breaking and Wetting Action

A combined crumbling and flooding effect on the cap is desired.Referring to FIG. 11, the nozzles are controlled to provide a two-stepmodulation, which means that each nozzle operates, in a first step, bypulsed injection of jets of constant duration, and in a second step bycontinuous injection. The nozzles are operated in crossed combination,i.e. the next nozzle starts when the previous nozzle has not stopped itsoperation yet.

Example 5 Cap Submerging Action

The desired action involves first gas stripping to support the cap andthen lowering the cap into the liquid. Here (see chart of FIG. 12), aconstant injection mode is provided, with intermittent air jets ofconstant duration, delivered in turn by each of the installed nozzles.In other words, the time interval between two successive jets of anozzle is sufficient to cover a jet of each of the other nozzles. Onceagain this provides a very mild effect, which can only be used for theabove mentioned purpose.

Example 6 Sustained Medium Action

This operating mode, as shown in FIG. 13, is similar to that of Example1, i.e. with increasing modulation and crossed modulation, but isrepeated multiple times, here three times.

Therefore, the various modes may be summarized as follows:

A) Considering the jet of an individual nozzle:

1) Increasing or decreasing modulation—single step:

-   -   for an individual nozzle, the duration of actuation pulses and        the duration of pause pulses increase or decrease respectively        during the nozzle operating time.        2) Constant modulation—single step:    -   for an individual nozzle, both the duration of actuation pulses        and the duration of pause pulses remain constant to a preset        value throughout the nozzle operating time.        3) Increasing-decreasing-constant modulation—two steps:    -   like the previous cases, but with a continuous air injection of        preset duration at the end of each jet of the nozzle.        B) Considering the sequence of nozzles        1) Crossed combination    -   the next nozzle starts when the previous nozzle has not        completed its cycle yet.        2) Alternate combination    -   the next nozzle starts when the previous nozzle has already        completed its cycle. Each sequence may be performed once or        repeated N times (see Example 5 in which the sequence is a        succession of single actuations of each nozzle and this sequence        is repeated 5 times, or Example 6, which is the same modulation        as in Example 1, with repetition=3)

It shall be noted that each of the above examples is obviously a “punchdown”. Such punch down may be repeated N times a day.

The above disclosure clearly shows that the method of the presentinvention can fulfill the intended objects. Particularly, the variouspossible applications of a predetermined jet modulation rule for eachnozzle and sequential nozzle combinations provide disgregrating waveswhich submerge and break the entire cap, thereby flooding it withliquid. This occurs within a few seconds and with no violent action.

Due to a high extraction potential and action times as short as a fewseconds, the consumption of air or inert gas is minimized, and theproblems associated with flavor- and alcohol-stripping are henceconsiderably reduced.

The modulated-sequential control mode has been also experimentally foundto be effective even when nozzles are installed from the bottom, whenthis creates no hindrance (self-emptying slant-bottom tanks), therebyobviating the problems of similar prior art air-bubble systems.

Therefore, when allowed by the tank emptying and cleaning conditions,the nozzles may be also mounted to the bottom of the tank and verticallyextend therefrom. In this case, they may extend in linear fashion, whichmeans that the angle of divergence of the substantially L shape of thenozzles is 180°. Yet, nozzle control modes and air injection modulationare as defined by the above described and illustrated inventive method.

It shall be finally noted that, while reference has been always madeherein to air as the fluid in use, any fluid that is functionallyequivalent to air, e.g. an inert gas such as nitrogen, may bealternatively used, and in this sense the term air shall be intended,each time it is mentioned.

Variants and/or changes may be made to the method of controlled airinjection into a vinification tank and to the associated device of thepresent invention, without departure from the scope of the invention, asdefined in the following claims.

The invention claimed is:
 1. A method treatment of grapes comprising:providing a vinification tank with a gas injection device having: atleast three nozzles for the injection of compressed gas into thevinification tank, a distribution circuit including a separate supplyline for each nozzle, control valves on said distribution circuit forcontrolling gas flow to each nozzle, each of the control valves beingpresent on the respective supply line of each nozzle; independentlyactuating the control valves and cause injection of compressed gas inthe form of a plurality of gas pulses which are injected into thevinification tank through each one of said at least three nozzles,wherein said injection of compressed gas in the form of gas pulsescomprises a cycle of gas injection through each nozzle, each cycle ofgas injection comprising gas pulses through each nozzle, wherein thenozzles are activated in sequence with the at least three nozzlesstarting respective cycles of gas injection in turn, one after theother, such that cycles of subsequently activated nozzles are partiallyoverlapping over time.
 2. The method of claim 1, wherein each air jethas a duration between a minimum duration of 100 ms and a maximumduration of 15 s; and wherein the compressed gas has operating pressureranging from 2 to 7 bar.
 3. The method of claim 1, wherein each cycle ofgas injection through each nozzle is repeated multiple times per day. 4.The method of claim 1, wherein the method is executed after the stepsof: feeding the tank with crushed red grapes, allowing grape skins toseparate from liquid to form a compact layer cap above the liquid, andwherein the plurality of injected gas pulses are configured to providewaves in the liquid which break the cap, flooding it with liquid.
 5. Amethod treatment of grapes comprising: providing a vinification tankwith a gas injection device having: at least three nozzles for theinjection of compressed gas into the vinification tank, a distributioncircuit including a separate supply line for each nozzle, control valveson said distribution circuit for controlling gas flow to each nozzle,each of the control valves being present on the respective supply lineof each nozzle; inserting crushed red grapes into the vinification tank,allowing grape skins to separate from liquid to form a compact layer capabove the liquid, independently actuating the control valves and causeinjection of compressed gas in the form of gas pulses which are injectedinto the vinification tank through each one of said at least threenozzles, wherein said injection of compressed gas in the form of gaspulses comprises a cycle of gas injection through each of said at leastthere nozzles, each cycle of gas injection comprising gas pulses througheach nozzle, and wherein the cycles of gas injection through the atleast three nozzles form waves in the liquid which break the cap,flooding it with liquid.
 6. The method of claim 5, wherein each air jethas a duration between a minimum duration of 100 ms and a maximumduration of 15 s; and wherein the compressed gas has operating pressureranging from 2 to 7 bar.
 7. The method of claim 5, wherein each cycle ofgas injection through each nozzle is repeated multiple times per day. 8.The method of claim 5 wherein each of said cycles lasts a few tens ofseconds to minimize gas consumption and reduce problems associatedstripping of aromas and alcohol.
 9. A method treatment of grapescomprising: providing a vinification tank with a gas injection devicehaving: at least three nozzles for the injection of compressed gas intothe vinification tank, a distribution circuit including a separatesupply line for each nozzle, control valves on said distribution circuitfor controlling gas flow to each nozzle, each of the control valvesbeing present on the respective supply line of each nozzle; actuatingthe control valves and cause injection of compressed gas in the form ofgas pulses which are injected into the vinification tank through eachone of said at least three nozzles, wherein the compressed gas hasoperating pressure ranging from 2 to 7 bar.
 10. The method of claim 9,wherein each air jet has a duration between a minimum duration of 100 msand a maximum duration of 15 s.
 11. The method of claim 9, wherein saidcontrol valves are actuated independently of each other and wherein saidinjection of compressed gas in the form of gas pulses comprises a cycleof gas injection through each nozzle, each cycle of gas injectioncomprising a plurality of gas pulses through each nozzle.
 12. The methodof claim 11, wherein each cycle of gas injection through each nozzle isrepeated multiple times per day.
 13. The method of claim 11, wherein thenozzles are activated in sequence with the at least three nozzlesstarting respective cycles of gas injection in turn, one after theother.
 14. The method of claim 11, wherein the nozzles are activated insequence with the at least three nozzles starting respective cycles ofgas injection in turn, one after the other, such that cycles ofsubsequently activated nozzles are partially overlapping over time. 15.The method of claim 11, wherein the nozzles are activated in sequencewith the at least three nozzles starting respective cycles of gasinjection in turn, one after the other, and wherein cycles of subsequentactivated nozzles are not overlapping such that a first cycle of a givennozzle starts a delay time after end of the first cycle of a precedingnozzle.
 16. The method of claim 14, wherein said control valves areactuated such that frequency and duration of the gas pulses emitted byeach nozzle, in a same cycle of gas injection, are constant.
 17. Themethod of claim 15, wherein said control valves are actuated such thatfrequency and duration of the gas pulses emitted by each nozzle, in asame cycle of gas injection, are constant.
 18. The method of claim 14,wherein said control valves are actuated such that the gas pulsesemitted by each nozzle in a same cycle of gas injection comprises pulsesof increasing duration and/or wherein said control valves are actuatedsuch that the gas pulses emitted by each nozzle in a same cycle of gasinjection comprises pause times between consecutive pulses, said pausetimes presenting increasing duration.
 19. The method of claim 15,wherein said control valves are actuated such that the gas pulsesemitted by each nozzle in a same cycle of gas injection comprises pulsesof increasing duration and/or wherein said control valves are actuatedsuch that the gas pulses emitted by each nozzle in a same cycle of gasinjection comprises pause times between consecutive pulses, said pausetimes presenting increasing duration.
 20. The method of claim 9, whereinthe method is executed after the steps of: feeding the tank with crushedred grapes, allowing grape skins to separate from liquid to form acompact layer cap above the liquid, and wherein the plurality ofinjected gas pulses are configured to provide waves in the liquid whichbreak the cap, flooding it with liquid.